So what would be a better, easier and more balanced version? This is the Creations and House Rules forum, not the whine-about-rules-you-don't-like forum. Well I guess it can be that too, but then I expect someone to provide a solution.
To say that it's just useful in some situations doesn't make it a bad feat. Many other feats are only useful in a few situations.
Now, I have a few ideas that could make Power Attack more interesting. None of them are better, easier to use or more balanced than the current version though but perhaps you will find them useful:
1) Instead of a flat +2 bonus to damage, add +1d4 for one-handed weapons and +1d6 for two-handed weapons. The average is the same but the potential for even greater damage is there. Add another dice for Paragon and a third dice for Epic tier games. This will of course make critical hits completely nuts.
2) Make it a -1 to hit for +2 to damage. This makes powerattacking with two-handed weapons even stronger than it already is. It's easier to use though.
3) Remove the penalty completely. Make it so that you only deal extra damage against enemies who grant combat advantage. Is that better? It removes all control over when to use the feat from the player but on the other hand it automatically works in a situation when most people would use it anyway. It's probably too powerful and not a good idea to do this.